MassMessage is being deployed to Wikimedia wikis with two limitations: an additional user right and a configuration decision that limits its capabilities.

The additional user right is called "massmessage" and is only assigned to local administrators (sysops) by default. Previously anyone on an on-wiki access list (including non-administrators) could easily send out mass messages. Your local community should consider its options: adding a viral user group (i.e., anyone in the user group can add others to the same user group), allowing administrators to assign the user right in a specific user group, or setting up a "requests" page queue for administrators to process. Please be cognizant of the fact that MassMessage, at its core, does little more than automate what any user could do with browser tabs without even logging in.

The configuration decision restricts local users (except on Meta) from making cross-wiki deliveries. Again, any user can easily open browser tabs and post cross-wiki without even logging in, but the option in the MassMessage extension was disabled, for now.

Only on Meta-Wiki (this wiki), any user with the "massmessage" user right (administrators and massmessage senders) can send messages to any Wikimedia wiki. In addition, on this wiki there is a wrapper template ({{target}}) that should be used for input lists.

The subject line is fairly straightforward. It may not exceed 240 bytes (doing so causes truncated edit summaries).

The body is the text of the message you wish to deliver.

For messages longer than a few lines, the body should be just a few lines of introduction with a link to the actual message, translatable with the Translate extension (example; tutorial) – unless it's a user who opted in or a project page in the same language as the message.

Use links in the form [[m:Special:MyLanguage/Page name here]] if the page has translations and the Translate extension.

If you are sending a message in English to non-English wikis, please wrap your message with <div lang="en" dir="ltr" class="mw-content-ltr"></div>.

Include a link to Global message delivery or another page where users can understand why and how the message was delivered and give feedback (like the user talk of the sender, the Meta-Wiki or mediawiki.org page of the project).

If not accomplished by the previous point, include a link to the distribution list — for example, "(Wrong page? Fix here.)".

Avoid embarrassment and double-check that you are sending to the right distribution list. Effective July 10, 2013, you agree to the following: you are fully responsible for any mistakes (including typos in the body text, inappropriate recipients lists, etc.) and you commit yourself to manually cleaning up any messes you create.

If the message is going interlanguage or interproject, please manually test the message at a range of these wikis to ensure that links work as expected, also refer to Special:Interwiki.